Signalling relay test bench

The bench is designed for testing signalling relays during scheduled repair in the signalling workshop: neutral and polarized DC relays, and combined, code and two-element vane AC relays. It determines the armature pick-up and drop-away voltage and current, the slow-operate and slow-release times, coil resistance, contact resistance and the insulation resistance between coils, contacts and the relay frame.

The relay is plugged into the base of an interchangeable panel, after which the measuring system ramps the coil voltage up or down smoothly and records the moment the contacts switch. DC and AC voltages are produced by programmable sources, transition times are measured from the closing of the contact groups, and for two-element vane relays two independent channels with adjustable phase shift between the local and track elements are provided. The bench is built as a workstation with an instrument rack: relay bases are set into the worktop, the rack houses the power sources, measuring modules and switching unit, and a pull-out shelf carries the computer with the test software.

The software stores the parameter limits for each relay type, compares the measurements with the tolerances and prints a report with a pass/fail conclusion. On request the bench is supplied with additional interchangeable panels for less common base types, a contact adjustment fixture, a microscope for inspecting contact surfaces and a module for testing heavy-duty contact relays at currents up to 10 A.